<template>
	<hx-navbar :is-back="false" title="商城分类"></hx-navbar>
	<view class="u-wrap">
		<view class="u-search-box">
			<view class="u-search-inner" @click="toSearch">
				<u-icon name="search" color="#909399" :size="28"></u-icon>
				<text class="u-search-text">搜索</text>
			</view>
		</view>
		<view class="u-menu-wrap">
			<scroll-view scroll-y scroll-with-animation class="u-tab-view menu-scroll-view" :scroll-top="state.scrollTop" :scroll-into-view="state.itemId">
				<view
					v-for="(item, index) in state.tabbar"
					:key="index"
					class="u-tab-item"
					:class="[state.current == index ? 'u-tab-item-active' : '']"
					@tap.stop="swichMenu(index)"
				>
					<text class="u-line-1">{{ item.name }}</text>
				</view>
			</scroll-view>
			<scroll-view :scroll-top="state.scrollRightTop" scroll-y scroll-with-animation class="right-box" @scroll="rightScroll">
				<view class="page-view">
					<view class="class-item" :id="'item' + index" v-for="(item, index) in state.tabbar" :key="index">
						<view class="item-title">
							<text>{{ item.name }}</text>
						</view>
						<view class="item-container">
							<view class="thumb-box" v-for="(item1, index1) in item.children" :key="index1" @click="toGoodsList(item1.id)">
								<image class="item-menu-image" :src="item1.categoryPic" mode=""></image>
								<view class="item-menu-name">{{ item1.name }}</view>
							</view>
						</view>
					</view>
				</view>
			</scroll-view>
		</view>
	</view>
</template>
<script setup lang="ts">
import { nextTick, reactive } from 'vue';
import { onReady, onLoad } from '@dcloudio/uni-app';
import { getTree } from '@/api/product/category';
interface State {
	scrollTop: number;
	oldScrollTop: number;
	current: number;
	menuHeight: number;
	menuItemHeight: number;
	itemId: string;
	tabbar: Array<any>;
	menuItemPos: Array<any>;
	arr: Array<any>;
	scrollRightTop: number;
	timer: any;
}
const state = reactive<State>({
	scrollTop: 0, //tab标题的滚动条位置
	oldScrollTop: 0,
	current: 0, // 预设当前项的值
	menuHeight: 0, // 左边菜单的高度
	menuItemHeight: 0, // 左边菜单item的高度
	itemId: '', // 栏目右边scroll-view用于滚动的id
	tabbar: [],
	menuItemPos: [],
	arr: [],
	scrollRightTop: 0, // 右边栏目scroll-view的滚动条高度
	timer: null, // 定时器
});
onLoad(() => {
});
onReady(() => {
	getCategory();
});
const getCategory = () => {
	getTree().then((response) => {
		state.tabbar = response.data;
		getMenuItemTop();
	});
};
// 点击左边的栏目切换
const swichMenu = async (index: number) => {
	if (state.arr.length == 0) {
		getMenuItemTop();
	}
	if (index == state.current) return;
	state.scrollRightTop = state.oldScrollTop;
	nextTick(() => {
		state.scrollRightTop = state.arr[index];
		state.current = index;
		leftMenuStatus(index);
	});
};
// 获取一个目标元素的高度
const getElRect = async (elClass: any, dataVal: any) => {
	new Promise((resolve, reject) => {
		const query = uni.createSelectorQuery();
		query
			.select('.' + elClass)
			.fields(
				{
					size: true,
				},
				(res) => {
					// 如果节点尚未生成，res值为null，循环调用执行
					if (!res) {
						setTimeout(() => {
							getElRect(elClass, '');
						}, 10);
						return;
					}
					// state?[dataVal] = res.height;
					resolve(true);
				}
			)
			.exec();
	});
};
// 观测元素相交状态
const observer = async () => {
	state.tabbar.map((val, index) => {
		let observer = uni.createIntersectionObserver(state);
		// 检测右边scroll-view的id为itemxx的元素与right-box的相交状态
		// 如果跟.right-box底部相交，就动态设置左边栏目的活动状态
		observer
			.relativeTo('.right-box', {
				top: 0,
			})
			.observe('#item' + index, (res: any) => {
				if (res.intersectionRatio > 0) {
					let id = res.id.substring(4);
					leftMenuStatus(id);
				}
			});
	});
};
// 设置左边菜单的滚动状态
const leftMenuStatus = async (index: number) => {
	state.current = index;
	// 如果为0，意味着尚未初始化
	if (state.menuHeight == 0 || state.menuItemHeight == 0) {
		await getElRect('menu-scroll-view', 'menuHeight');
		await getElRect('u-tab-item', 'menuItemHeight');
	}
	// 将菜单活动item垂直居中
	state.scrollTop = index * state.menuItemHeight + state.menuItemHeight / 2 - state.menuHeight / 2;
};
// 获取右边菜单每个item到顶部的距离
const getMenuItemTop = () => {
	new Promise((resolve) => {
		let selectorQuery = uni.createSelectorQuery();
		selectorQuery
			.selectAll('.class-item')
			.boundingClientRect((rects: any) => {
				// 如果节点尚未生成，rects值为[](因为用selectAll，所以返回的是数组)，循环调用执行
				if (!rects.length) {
					setTimeout(() => {
						getMenuItemTop();
					}, 10);
					return;
				}
				rects.forEach((rect: any) => {
					// 这里减去rects[0].top，是因为第一项顶部可能不是贴到导航栏(比如有个搜索框的情况)
					state.arr.push(rect.top - rects[0].top);
					resolve(true);
				});
			})
			.exec();
	});
};
// 右边菜单滚动
const rightScroll = async (e: any) => {
	state.oldScrollTop = e.detail.scrollTop;
	if (state.arr.length == 0) {
		getMenuItemTop();
	}
	if (state.timer) return;
	if (!state.menuHeight) {
		await getElRect('menu-scroll-view', 'menuHeight');
	}
	setTimeout(() => {
		// 节流
		state.timer = null;
		// scrollHeight为右边菜单垂直中点位置
		let scrollHeight = e.detail.scrollTop + state.menuHeight / 2;
		for (let i = 0; i < state.arr.length; i++) {
			let height1 = state.arr[i];
			let height2 = state.arr[i + 1];
			// 如果不存在height2，意味着数据循环已经到了最后一个，设置左边菜单为最后一项即可
			if (!height2 || (scrollHeight >= height1 && scrollHeight < height2)) {
				leftMenuStatus(i);
				return;
			}
		}
	}, 10);
};
// 跳转商品搜索
const toSearch = () => {
	uni.$hxRouter.push({url:'/pages/product/goods-search/index'});
};
// 跳转商品列表
const toGoodsList = (categoryId: string) => {
	uni.$hxRouter.push({url:'/pages/product/goods-list/index?categoryId=' + categoryId});
};
</script>

<style lang="scss" scoped>
.u-wrap {
	height: calc(100vh);
	/* #ifdef H5 */
	height: calc(100vh - var(--window-top));
	/* #endif */
	display: flex;
	flex-direction: column;
}

.u-search-box {
	padding: 18rpx 30rpx;
}

.u-menu-wrap {
	flex: 1;
	display: flex;
	overflow: hidden;
}

.u-search-inner {
	background-color: rgb(234, 234, 234);
	border-radius: 100rpx;
	display: flex;
	align-items: center;
	padding: 10rpx 16rpx;
}

.u-search-text {
	font-size: 26rpx;
	color: $u-tips-color;
	margin-left: 10rpx;
}

.u-tab-view {
	width: 200rpx;
	height: 100%;
}

.u-tab-item {
	height: 110rpx;
	background: #f6f6f6;
	box-sizing: border-box;
	display: flex;
	align-items: center;
	justify-content: center;
	font-size: 26rpx;
	color: #444;
	font-weight: 400;
	line-height: 1;
}

.u-tab-item-active {
	position: relative;
	color: #000;
	font-size: 30rpx;
	font-weight: 600;
	background: #fff;
}

.u-tab-item-active::before {
	content: '';
	position: absolute;
	border-left: 4px solid $u-type-primary;
	height: 32rpx;
	left: 0;
	top: 39rpx;
}

.u-tab-view {
	height: 100%;
}

.right-box {
	background-color: rgb(250, 250, 250);
}

.page-view {
	padding: 16rpx;
}

.class-item {
	margin-bottom: 30rpx;
	background-color: #fff;
	padding: 16rpx;
	border-radius: 8rpx;
}

.class-item:last-child {
	min-height: 100vh;
}

.item-title {
	font-size: 26rpx;
	color: $u-main-color;
	font-weight: bold;
}

.item-menu-name {
	font-weight: normal;
	font-size: 24rpx;
	color: $u-main-color;
}

.item-container {
	display: flex;
	flex-wrap: wrap;
}

.thumb-box {
	width: 33.333333%;
	display: flex;
	align-items: center;
	justify-content: center;
	flex-direction: column;
	margin-top: 20rpx;
}

.item-menu-image {
	width: 120rpx;
	height: 120rpx;
}
</style>
